This application claims the priority of German Application No. 197 33 787.2, filed Aug. 5, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention involves a belt roller for a safety belt system of a passenger seat, especially in a motor vehicle, with a pivoted hollow shaft used for rolling up a belt band and with a torsion rod structure placed coaxially inside the hollow shaft and connected with a twistlock thereto, to which devices to adjust its energy absorption capacity are allocated depending on the weight of the person sitting on the passenger seat, and with a blocking mechanism which can be brought to make an effective connection with the torsion rod structure to stop the hollow shaft in response to a defined jerk on the belt band.
Such a belt roller is known from German Patent document DE 27 27 470 A1. The belt roller has a hollow shaft, on which the belt band to be pulled out is rolled up. The hollow shaft is penetrated coaxially by a torsion rod structure shaped like a single torsion rod, the clamping length of which is adjustable by a sliding sleeve. The relocation of the sliding sleeve and hence also the change in the energy absorption capacity of the torsion rod is accomplished through the use of a cable pull control which connects directly to a seat surface of the passenger seat. Depending on how deep the seat surface is depressed by the weight of the person sitting on this seat, an appropriate relocation of the sliding sleeve necessarily takes place and, accordingly, the limit desired in each case is imposed on the belt power. The torsion rod is connected to the hollow shaft with a twistlock on one side and can be activated on the opposite side by a stopping mechanism, which is activated in the well-known manner by a jerk on the belt band of the safety belt during its acceleration.
From German Patent document DE 43 44 656 C1 an additional belt roller is known, the belt power limitation of which is adjustable in accordance with the weight of the person sitting on the passenger seat. For this purpose, a conically shaped torsion rod has been provided, which is also axially adjustable by a corresponding activation mechanism, thus creating the corresponding change in the energy absorption capacity of the torsion rod.
It is the purpose of the present invention to create a belt roller of the above-mentioned type which provides a simple means of adjusting the belt power limitation to account for the different types of people having different weights who sit on the passenger seat.
The present invention solves this task by the fact that the torsion rod assembly has a torsion rod and at least one torsion sleeve coaxially surrounding it, and that the stopping mechanism is equipped with at least two stopping element sections which can be adjusted either individually or jointly to the (at least one) torsion sleeve or to the torsion rod by means of a control mechanism depending on the energy absorption capacity to be applied. This permits a gradual change in the energy absorption capacity, with the number of steps to set the energy absorption capacity being defined by the number of torsion sleeves mounted radially and coaxially to enclose the torsion rod on the outside.
According to the invention, the means to change the energy absorption capacity of the torsion rod assembly are provided directly in the area of the stopping mechanism and not--as in the current state of the art--on the opposite side of the belt roller. For this reason, there is a savings on construction components and a space-saving arrangement. The axial shift of the stopping sections makes it possible for all the stopping sections to act simultaneously, so that the torsion rod assembly can be blocked either partially or totally by the stopping blocking mechanism.
In one preferred embodiment of the invention, the stopping element sections are located on a common stopping element, with the stopping element sections being placed at intervals in the direction of adjustment in such a way that the stopping element section activating the torsion rod is the first to achieve an effective connection with the torsion rod. This configuration ensures that the torsion rod itself is activated in the first stage of the belt power limitation. During the second stage, a joint activation of the torsion rod and the first torsion sleeve takes place, and, if possible, in a third stage the supplementary activation of the third torsion sleeve takes place, and so on.
In another preferred embodiment of the invention, the stopping element sections are shaped as stopping gear elements that are adjustable radially to the torsion rod assembly, and, both on the torsion rod and on the (at least one) torsion sleeve, corresponding ring gears are provided. Due to the radial adjustability of the stopping gear elements, no additional construction space is required for the belt roller in the axial direction. Preferably, the ring gears are designed as toothed gears mounted on the adjacent front sides of the torsion rod and of the (at least one) torsion sleeve. The stopping gear elements are designed as pawls.
In another preferred embodiment of the invention, at least one catch that can be adjusted by the control unit is assigned to the stopping element. The catch limits the stopping element in its adjustment path for a gradual effective connection with the torsion rod assembly. The catch can preferably be moved electromagnetically between its rest position and its operating position, which appropriately blocks the stopping element, with the shift of the catch by the control unit resulting from an electronic recognition of the weight in the area of the seat surface of the passenger seat.
In yet another preferred embodiment of the invention, a gear notch of the ring gear on the torsion rod is configured in such a way that the respective stopping gear element meshes in both the first and the last step of the effective connection with the torsion rod assembly. This guarantees that, with extremely simple means, the torsion rod assembly is effective at all stages of the belt power limitation.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.